Thermostatic Shower Valve

[Degs]

First time up so be gentle with me. Went round to my mates as he has says the water pressure at the shower head is less than it use to be, I advised him to get another shower head as the old one was half blocked and was a sealed unit. After turning up the boost knob up on the pump the pressure increased but when you turn the L/H flow knob ( its one of those horizonal mixers) to off the pump keeps running, if you turn the R/H hot and cold knob a touch the pump stops.
Cheers Degs

 

[Puddle]

Well presume L/H flow knob is in fact the hot and cold control and the R/H hot and cold knob is the on /off ,maybe knobs wrong way round ?

 

[Degs]

Well presume L/H flow knob is in fact the hot and cold control and the R/H hot and cold knob is the on /off ,maybe knobs wrong way round ?

Thanks for that info I will check it out, but why would it of been ok for the last couple of years ?
Cheers Degs